1. Field of the Invention
The present invention relates to an organic electroluminescent display, and more particularly, to an organic electroluminescent display having a signal input portion including power supply lines for receiving a power supply voltage and data lines for receiving data signals, the power supply line and data line being separated from each other by an optimal distance difference or gap to prevent unnecessary parasitic capacitance.
2. Description of the Related Technology
Generally, an organic electroluminescent display is a flat panel display that emits light when an electric field is applied to a fluorescent material formed on a glass substrate or a transparent organic film. The phenomenon of the fluorescent material (which may be a semiconductor) emitting light when placed in an electric field is known as electroluminescence.
Recently, a liquid crystal display (LCD), an organic electroluminescent display (OLED), and the like have widely been used in mobile information devices because they are, among other benefits, lightweight, and thin. The organic electroluminescent display, whose brightness and viewing angle are superior to the LCD, has attracted much attention.
Typically, an active matrix organic electroluminescent display (AMOLED) includes a pixel with red (R), green (G) and blue (B) sub-pixels. Each of the R, G and B sub-pixels includes an organic electroluminescent diode. Each organic electroluminescent diode includes an anode, a cathode, and an R, G or B organic emission layer interposed between the anode and the cathode. When a voltage is applied between the anode and the cathode, light is emitted from an organic layer formed of the R, G or B organic emission layer corresponding to the color of the organic emission layer.
Further, the AMOLED drives N×M organic electroluminescent diodes by using a voltage programming method or a current programming method.
FIG. 1 is a cross-sectional view of a signal input portion for applying a signal to a display panel portion in a conventional organic electroluminescent display.
Referring to FIG. 1, the cross-sectional view of the display panel portion in the organic electroluminescent display has data lines portion Z for receiving data signals, a first power supply line portion X, and a second power supply line portion Y for receiving a power supply voltage at both sides of the data lines portion Z.
Further, FIG. 1 illustrates a plurality of data lines connecting a data driver and a display panel provided in the display panel portion of the conventional organic electroluminescent display. Here, the plurality of data lines are arranged in a spider tie shape, which is a simple shape made by lines evenly diverging away from a center line, to transmit predetermined data signals to the display panel.
To manufacture a display panel portion like the embodiment shown in FIG. 1, firstly, a substrate 100 formed of glass, synthetic resin or the like is prepared. Then, one of a silicon dioxide (SiO2) layer, a silicon nitride (SiNx) layer, and a stacked layer of the silicon dioxide/nitride layer is formed as a buffer layer 110 on the substrate 100, which prevents impurities from outflowing from the substrate 100.
Here, the buffer layer 110 is not essential, and therefore sometimes not used
Then, a gate insulating layer 120 is formed on the entire surface of the substrate 100, and a plurality of data lines 130 are patterned across the surface of the substrate 100 at regular intervals to apply the data signals to the display panel.
Here, the data lines are formed of at least one of chrome (Cr), molybdenum (Mo), aluminum (Al), silver (Ag), and alloys thereof.
Then, an interlayer-insulating layer 140 is formed on the gate insulating layer 120 and the plurality of data lines 130 across the surface of the substrate 100. A predetermined power supply electrode is then formed on the entire surface of the interlayer-insulating layer 140. Thus, a predetermined power supply line 150 is formed by depositing the power supply electrode in the first power supply line portion X, the second power supply line portion Y, and the data lines portion Z.
Accordingly, parasitic capacitance C is formed between each of the plurality of data lines 130 and the power supply line 150. The parasitic capacitance C causes load artifacts such as signal loss, signal distortion, signal delay, and overpower which deteriorate the emission characteristics of the organic electroluminescent display.
Here, the power supply line is formed of at least one of chrome (Cr), tungsten (W), molybdenum (Mo), aluminum (Al), silver (Ag), and alloys thereof.
Then, one of a silicon dioxide (SiO2) layer, a silicon nitride (SiNx) layer, and a stacked layer of the silicon dioxide layer/nitride layer is formed as a passivation layer 160 completely covering the power supply line 150 formed in the first power supply line portion X, the second power supply line portion Y, and the data lines portion Z.
Then, at least one of an acryl resin, a benzo-cyclo-butene (BCB) resin, a polyimid (PI) resin, a spin on glass (SOG) resin, an acrylate resin, a poly phenol resin, and the like is formed as an organic layer, i.e., a planarization layer 170, on the passivation layer 160.
Then, a pixel defining layer (PDL) 180 is formed on the entire surface of the planarization layer 170. The pixel defining layer 180 is formed of at least one organic material such as an acryl resin, a benzo-cyclo-butene (BCB) resin, a polyimid (PI) resin, a spin on glass (SOG) resin, an acrylate resin, and a poly phenol resin.
In the foregoing described signal input portion of the conventional organic electroluminescent display, the gap between the power supply line and the data lines is so narrow that the resulting parasitic capacitance increases the load, thereby causing signal loss, signal distortion, signal delay, and the like.